In case of fire occurring in any unit in an urban high-rise or super high-rise building, if no fire engine can reach the height of the unit on fire, the high temperature and flame in the unit on fire are sufficient to burn most of the articles in its upper, lower, left and right neighboring units if the fire in the said unit is not put out in time, which may cause more and bigger fire disasters.
Firefighting of urban high-rise and super high-rise buildings is still a worldwide firefighting challenge till today. As high-rise building firefighting needs grow, the firefighting height of fire engines has developed and reached 100 m level. However, their fabrication cost, road assistance and weather condition among other requirements cannot always be affordable by all medium and small cities having high-rise buildings. Meanwhile, restrained by the technological and safety level of the present stage, firefighting height of fire engines cannot be increased without limit to accommodate for the height increase of urban high-rise buildings. Even with the currently available fire engines with a 100 m firefighting height, it is also difficult to cope with a fire occurring in high-rise or super high-rise buildings measured more than 100 m in height. No to mention the firefighting height of the fire engines in most cities is below 50 m, which can only be used to effectively putting out a fire occurring on the 20th floor and lower.
Besides the elevated fire engine which can be used for fire extinguishing in high-rise buildings, presently there are two technologies that can largely be employed for putting out fires in high-rise buildings: missile type fire extinguishing device and abrasive hole-drilling fire extinguishing device.
According to a news report dated Jul. 10, 2013, missile fire extinguishing has undergone a live missile fire extinguishing test with success achieved, which will add another means of fire extinguishing for high-rise and super high-rise buildings. However, since the tail end of its ballistic trajectory appears in a parabolic shape, a certain distance and space is needed to launch the missile when it is applied in densely distributed building groups in cities, especially when it is used for putting out a fire in high-rise and super high-rise buildings. During fire extinguishing on an urban street where the space is limited, its use may be restrained if the object is too close to the launching point. And the use and maintenance of dangerous ammunitions and precision control devices by the fire brigades will also be somewhat difficult.
Abrasive hole-drilling fire extinguishing device (water jet technology) is a fire extinguishing device named COBRA which was invented by a foreign company. There are also some manufacturers in China producing similar fire extinguishing device. This kind of device needs a power machine with scores of horsepower to produce more than 300 kilograms high-pressure water, which is mixed with iron sand abrasive compound to jet impact the wall or iron plate to form small pores, through which high-pressure water mist is produced and used for fire extinguishing. However, both the power and the volume of it are fairly big, and the equipment is fairly complicated. Most of such devices need to be mounted on various kinds of large or small vehicles in order to have them transported to the fire extinguishing site.
Abrasive hole-drilling fire extinguishing device partially belongs to high-pressure vessel, and its application, repair and maintenance are quite restricted. The mixture of high-pressure water produced by abrasive hole-drilling fire extinguishing device and abrasive sand may penetrate 1 cm thick iron plate or ordinary construction materials with a thickness of appr. 20 cm. However, it cannot penetrate high-rise building walls such as thick hollow brick walls, partition walls and load-bearing walls with a thickness of more than 40 cm, as well as compound walls built by using multiple types of materials and double-layer biparting household burglarproof doors. Since it is based on abrasive jet technology, holes can be effectively drilled only when a certain range is kept for the jet flow produced. Away from the core section of the range, hole-drilling is impossible in the rupture section. Therefore, the penetration depth of an abrasive hole-drilling fire extinguishing device is limited.
Of course, there are many other fire extinguishing devices which can penetrate an object. However, these cannot be directly used for firefighting of high-rise and super high-rise buildings. For example, there is kind of fire engine abroad, whose telescopic arm has percussion bit on it, which can be used to drill through the shell of an aircraft for the purpose of fire extinguishing. However, due to its huge size, it cannot enter a high-rise building for fire extinguishing. Other methods include the use of pneumatic, hydraulic or electric percussion drill, which can be employed to penetrate cars or shells made of thin materials. However, percussion strikes are not applicable for penetration of hard and thick materials. Furthermore, in case of big fires in oil depots caused by lightning strikes, the oil level cannot be reached often because the fire engine is not high enough or the foam is too light and the range is too short. Long-time combustion may cause an explosion, spreading to neighboring oil tanks.
A kind of fire extinguishing equipment that can quickly penetrate the building walls underthe dual effect of rotating bit and high-pressure water jet was disclosed in the Chinese patent with a utility model Patent No. ZL201220077916 and entitled “A kind of high-pressure water wall penetrating fire extinguishing device”, which can be used for high-efficiency wall penetrating and fire extinguishing. However, the said fire extinguishing equipment has the following shortcomings: Firstly, building walls cannot be penetrated by using high-pressure water alone. There must be a blend of abrasive sand as well as super high-pressure water in order to penetrate a building wall within a certain range. Secondly, limited range for high-pressure water jet wall penetration. Thickness of wall to be penetrated will not exceed 20 cm. Thirdly, the jet gun used for high-pressure water jet is special with a high reaction force, which can be held against only by shoulder. This structure can be pushed away by the high-pressure water and cannot be used properly (See COBRA abrasive hole-drilling fire extinguishing device). Fourthly, its long drill bit can easily shake when drilled into a wall body, for which supporting frame or guide rail must be provided. Otherwise, the drill bit can be easily broken or can easily drift. Fifthly, since electric motor is used as its power unit, it can be difficult to access electric power in case of fire.